These studies will explore the role of cholinergic and GABA-ergic projections originating in the media septum in modulating memory processes mediated by the hippocampus. Microinjections of cholinergic muscarinic receptor antagonists and GABA-A receptor agonists and antagonists into the medial septal area will be performed. The alternative hypotheses that these systems interact either synergistically or as opponent-processes in contributing to attentional or memory processes will be tested. Understanding septal-hippocampal cholinergic and GABA-ergic interactions may lead to novel pharmacotherapies for Alzheimer's disease by suggesting coadministration protocols for GABA-ergic and cholinergic drugs.